The seals of the Indus Valley Civilisation were made up of :

Steatite

The correct answer is Option (2) → Steatite

The seals of the Indus Valley Civilization were indeed primarily made from steatite.

Abundance of Steatite: Steatite, also known as soapstone, was readily available in the Indus Valley region. It was relatively abundant and easily accessible, making it a convenient material for crafting various artifacts, including seals.

Workability: Steatite is a soft and workable stone. It can be carved with simple tools and techniques, which made it well-suited for creating intricate and finely detailed designs. .

Durability: Steatite is a durable material that can withstand the test of time. This durability ensured that many of these seals have survived for thousands of years, providing valuable archaeological insights into the history and culture of the Indus Valley Civilization.

Smooth Surface: When polished, steatite has a smooth and slightly glossy texture, which was ideal for engraving detailed designs and inscriptions.